Telephone system



June 1 1926.

E. E HINRICHSEN TELEPHONE SYSTEM ori inal Filea July 14, 1920 2 Sheets-Sheet 1 l I I June 1 1926.

1,586,527 E. E. HINRICHSEN TELEPHONE SYSTEM Original Filed July 14. 1920 2 Sheets-Sheav 2 fiqfi.

Marginal /H van for: [d ward f. ///'n F/ChSfl? i r Patented June 1, 19 26.

fazowaanv ii. HINRIC ooMrAu'Y, incoaronarran,

. original application filed This inyention relates to teleplione sysirsn v, or N 'rEL'Ern0nEsYsTEMI QF NEW-YORK, N. Y. A COBIO arrow OF NEW Yoax.

iuiy i ig iaaa' Serial No; 396,143. Divid ed and this application filed September a aaaeza; se,ria m.6e5.2so;

tems and particularlyto subscriber-operated switching means for private branch exchange y This application is a working. application Serial No. 1920, which has been 396,143 filed July 14, issued as Patent No.

1,507,116 on September 2, 1924 toE. EcHin- The object an all relay system 0 bodying of the invention isto provide if small 1 capacity em- I all the conveniencesof a modern automatic telephone system suitable for use iira private residence or small business establishment where-the number of stations is so smallthat the regular employment of produces in an operator is unwarranted.

A. feature OftllQ present in the busy tone and ringing circuits where'- in busy tone andring ingcurrents are gen erated and controlled entirely by relays.

Two relays each with means for makingand breaking the circuit of the' other are employed as an interrupter for alternately'applying a source ofdirectcurrent to different primary windings of a; transformer.

plication 'ofdirectcurrent in thisnianner the second natiiig current of the proper characteristics arywinding an alter-,

for use as ringing current. Another pair, of

relays of the slow releasing type in a sim are employed to slowlyinter- These.

terrupted busy tone of relays which-arearrangedin such a c rcuit that two" coinplet e cycles" of said slow interruptions are ut lizedin energizing said last pair of binations. Theselast a circuit at aperiodic and this latter; circuit application of ringing known as the silent Other features inclu relays in all their possible comrelays in turn control but non-uniformirate is used tocontrol the cling novel circuit details will be more; apparent as-the descrip tion progresses.

In theaccompanying drawing one embodiment of this invention 15 d agramman .icallyillustrated; Fig. 1 represents a group of subscribers lines making incoming and with v the means "for outgoing 00111166310115 division of first" idle link" circuit.

invention resides LAP- a link circuit.

"to a calledjline, f

tothe G relays' of the known line relay,-

propagated and transmitted. from the, sub- Relay FT is an'a current in'iwliat are p p p I link cirouitis idle, thls relay is nnormal and ringiiigperiods.

trunk, iratlier to link circuitsfi Fig. 2 is a representation ofa link circuit I T A station to Sam (all. I I n the drawi gs; three station lines are shownfiwhicli, in the "system,

tio i line, tion is to respond to outgoing calls from initiatecircuit movement for connecting "the calling line to the each" line is" a Iout-ofli relay whose fund ion' is to respond tothe seizure} of a line 011* an incoming call to cut-off the line] relay and prevent the taking of an idle flink' circu t, as on anfoutgoing callQ 'also'responds tothe seizure of an idle link This relay circuit on an outgoingcall to cut-ofi the line relay and remove the calling condition a set up by said lineflrelay. lndividual to each link circuit there area number of re- {lays whose ifunct ons'ai'e,as*foll0ws;

Relay F P -t s' to oin a calling li gt' Relay G operates to 1 connect a" link circuit f Relay'TD operates v to connect the common numerical leads from .the; counting relays a particular relay is operated. 7

Relay P is an impulse-responsive relay and functions in themanner OftllflWBlL- "responding to impulses station, and suppliesfthrough its windings, talking battery for :the calling substation. Relay'H is a holding relay and-functions as the first slow, relay inthe modern step bystep systems. duringthe sending o'fimpulses, although its circuit/is continually'iopened for. short intervals during tliistime; f p

lotterrelay. When the position and in this condition renders the link circuit selectable. YVhenfthe link circuit is seized, this relay; becomes energized and transfers tlieselectable condition to the next idle link circuitl' lt also functions to put relay H under direct control of relay P.

Relay TK is a trunking relay. When a than a local;'connection,is dewould be sta- 101, 102 and link circuit whereby This relay remains. energized nwronnn. Aswan To wn'sTEan ELECTRIC Al'so, "individual to sired,.this relay. operates. in.the.sa1ne..1nanner as the'relayG and acts to cause a direct connection between a calling line and an idle trunk and to then restore the link circ-uit to normal.-

Relay ST is a stepping relay controlled by relay P to transmit the dial impulses to the counting relays.

Relay ON isa test relay on the busy ing relays will either remain deenergized or become energized. therebycausing: the operation of a relay A associatedwithrthe counting relays to remove the condition which marks the counting relays as idle. When-the counting relays-are in use, relay ON fails to operate-therebypreventing relay ST from locking and-periorming, its proper functions. 2

Relay TA. is a SIOKVrtO-I'BIQHSE: relay effectively responsire: to the: train: ofv impulses transmitted from the substation.v At the end of. the last impulse, relay TA deenergizes and extends a ground: through the con:- tacts of relay TC. to energize relay TD which. in. turn,., causes the. energization. of a. particular relay G.

'R-elay TC is. fast-relay. indirectly con.- trolled by relay TA. Its function, is-;- to connect; groundfr'ozn, the contacts of relay TA after. it has beendeenergized to the Winding of. relay TiDw It also .actstotransferralockingground from the. back contact of arelay B associated: Withthe counting relays to theback contactof axrelay C also associated with the counting relays. The function of relays A, B and C will be brought out hereinafter.

Relay TB is directly responsive, to-relay TA. and is of. the slow to-relea setype hereby after. the. relay-TA. is deenergized, .relay TB. still maintains: its-armatures in its? at? tracted position for an interval longenough tQlCH,l1S-.tll8 proper. energizatiomot therelay. TD;

Relay ET is.:a busy. test..relay. It, opert ates when. the called. line isbusy,v cuts ofl. the sleeve of the called line frornfrelay; TR and transmits busy tone. to the calling line. It. opens; the circuit of; relay ST to .prevent any displacement. of the apparatus; should thecallingg subscriber attempt to. dialagain. Relay BT, also acts vasthe battery. feed supply coils for thecallediline'.

Relay TR is a relay responsive to the idle condition-of the calledline. When BTifails tov operate TR becomes energized: and opens the circuitof relay. ST, inthis way performing the same function! as that pointed. out for-relay. BT. Upon operation it marks. the called line as. busy:

Relay G6) startsthe ringing. interruptei's and connects the. calledline to the ringing leadsa. This. relay is .shorhcircuitedl by the relay R Wheirit. in turn operates;

and depending, or ldle condition-otthe. counts Relay, R isthe ringing, relay. Upon the operation-=of'relay GO,.ringing current is supplied through one of its windings to the called line and, being a marginal relay, will notattract its armatures-until the subscriber by taking his receiver oil the hook, so reduces the resistance of the substation loop that" sufficient current Will flow to cause the energization of. this relay. 'lhereupon,v relay Rshort circuits the windings of relay GO and locks itself in a local circuit to maintain the. conversational circuit closed.

Relays-Ag, Band C, which are connnon to the linkv circuits, have. the fol-lowingi functions:

Relay in link: circuits-toindicate. the idle condition oftthe countingrelays. When the subscriberremoves his receiver from the hook and relay F functions; ifthe counting: relays are idle and he maytlrerefore operate his dial sender.

dial-tone will. be. transmitted from a back contactof relay A to the. calling subscriber. Relay A. therefore also acts to-cut. oil. the dial tone: andthe operating battery from the link circuits Wheat-he counting relays are in use.

Relay B-isa: slow-to-release relay whose functlonzis to prevent the lockingofrelays ST should a. called. subscriber fail to notice the;absence of. dial tone.

Relay C, cooperateswith relay. ST. It cuts off the'holdingground.from relay ST so, that upon. the-- end. of. the. impulse, relay ST. will be deenergized. Relay C functions tmoperate. the counting relays.

The actions. andinteractionsof these. re

layswill.be'nicn'e apparent fronra description of. the: establishment. of a station to station call.

Whemthe subscriber. at. substation 1011cmoves .liisreceiver from its switchhook, line relay 201. becomes-energized through acircuit. includingbattery, .Winding of relay 20. inner. armature:v and; baclrcontactv of relay 203, the loop. offsubstation 101,. back contact andouter armatureof relay 203 to ground. Relay. 201 attracts itsarinatures and extends a circuitfrom battery, winding, of'relay 200, back contact andQinner,right-hand armature oli'relay. 207, front contact and inner right handiarmature of'relay; 208 (assuming the first. link, circuit tobe in. use), conductor 210; contact. and armature 211 of relay 201, back. contact. and. outer. left-hand armature ofrela-y203' toground. Relay 206 is energized infthis. circuit. r

The GIIGlJglZtltlOl'hOf relay. 201 also closes a circuit from grounch outer. left-'hanclarmature and back contactof relay. 20.3,. armature 211 and its. associatedcontact ofrelay 201, contactandarmature 2.14 of, relay 201, lefthand. Winding of relay. 212, conductor 218, back: contact and outer left-handarmature of relay. 207, front, contact and outer-left.-

actse to supply. dial tone to the hand armature of relay 208 to battery. Re-

212 is energized in this circuit and lay three left-hand armatures, conthrough its nects the calling line 101 to the link circuit "400; As soon as'relay 212 is energized a is extended from theright-handjan' ground matureof relay 206, normal contacts of the inner left-hand armature of relay 215, outer left-hand armature and front contact of relay 212 winding of cut 101i relay 203 tobattery. Relay 203 becomes energized and cuts off the line relay 201 which 1n turn becomes deenergized. Theloop of the calling substation now causes the energization'ot relay 216 whereupon a. circuitis extended from ground, winding of relay 401, conductor 214, left-hand armature and contact of relay 216, inner right-hand armature and back contact ofrelay 215, left-handwinding of relay 207 to battery. Relay 207 is energized in this circuit and mature and its outer left-hand armature,

extends the starting wires to the next idle link circuit in the same manner as relay 208 as the holding relay 206 ,is energized;

Through the outer right-hand armature of relay 207 and the left hand armature of relay 206, ground is placed: on conductor 402 thence through the outer left-hand armature and back contact of'relay 403,"the back contact and inner left-hand armature of relay 404, to the left-hand Winding of relay 405.

The left-hand winding of relay 405, how

ever, is short-circuited at this time due to a connection from ground, the right-hand ar a. the conductor 409, a tone.

extends over the con-' mature and front contact of relay 216, com

ductor 406 to the winding of relay 405. The a resistance 407 prevents the short-circuiting of the battery.

of relay 206 are-supplied and the winding with current fiowlng through the windings relay is energized of relay 401,this latter and, through itsnarmature, causes the energization of relay 408 energized so that it "buzzes and sets up on This tone is used as a dial tone and ductor 409, through the condenser 410, the

outer left-hand armature ings of relay :404 nndftheir connection .to* the maln conductors! of link c1rcu1t 400,

through its inner right-hand ar-H battery, front contact and inn er right-hand armature left-hand armature of relay 416 back contact and left-handarmature of "relay 420.; Imm-ediately a circuit "is estab- 'lished from battery, the-'right-hand arma-' 'ture and back contact of relay 411, conducfront contact y of relay on conductor 402.

'ductor 402; y from the ground on the left-hand winding of relay "hand ductor 418 thence to the winding of relay, which, because its oir-" cuit is made through its back contact and armature, is alternatelyenergized and de oirelay .conductor 412, back contact and vouter right-hand armature of relay 419, the right-hand winding not relay 404 to battery. the inducti e relation or the two wind this dialstone is transmitted to the calling substation 101. The connection is now in a stable conditionawaiting the sending of'a series. of impulses from the calling substation. I i

Let it be assumed that the subscriberat substation 101 wishes to establish a'connection to substat on 102. He thereupon manipulates his dialto! send series of two impulses which are in the, form of two'shortinterruptions of hisline circuit. Relay 216 responds to this'by retracting its armatures finally moving them to the attracted position where they remain juntil the' twice in quick succession and 'end of the conversation.

Upon the first retraction of the armatures of relay 216,"the ground is removed front the conductor 406 whereupon relay'i405 becomesenergized and attracts its armatures.

Relay 405 looks up in a circuit including the right-hand winding of relay 405 of relay 405, normal contacts of the inner 422, conductor tor i414, right hand winding of relay 419,

a ormal contacts of the left-hahd, armature. "ofrelay 421, outer right-hand armature'and' 405 to the ground Relay 419 becomes energized, and-through its left-hand winding,

front contact andinner left-hand armature of relay .419 looks to thegroundon-con- A circuitiis now established 405' through the front contact and outer right-hand armature of relay 405,

outer left-hand armature andfront contact of relay 419,.winding of relay 421 to bat tery and groundfRelay 421bec0mes energized in this circuit and attracts its arma-h tures. 'Thereu'pon a circuit is established c a from ground, the alternate contact and Since the left-hand winding of relay 207 j right-hand armature of relay V421 tov the winding, of'relay 423. Relay 423 is energized in thiscircuitfl Through its-right armature it vplaces aground on congized until the counting relays have become i ack ntaotidle. Q i

By its l'eftehand armature, relay" 423 places aground on-the winding of'relayr422 which operates, whereby the. circuit previously described for the locking" of relay 405 is now replacedby a circuit extending fronr ground, the left-hand armature and baiclc contact of relay 424, conductor 417, inner. left-hand armature and alternate contact of relay 422, inner right-hand armature and" front contact of relay 405, and righthand winding; of relay 405 to battery'. A circuit is-now estabislied from battery, the windingrof relay 424, conductor 415, front Contact and: inner right-hand armature of relay 419;; left-handarmature and alternate contactof relay 421; outer right-hand armature: and front. contact of relay 405- to the ground supplied over conductor 402*for the left-hand Winding. of relay 405. This causes the 'energization of. relay 424 whereby the lockin egroinid for the right-hand Winding of relay 405 is removed;

Through its rip ht-l-iand armature, relay 424 placcs-a ground on conductor 425 which extends through the normal-contacts of the inner ri-grhthand armatu-revof relay 217 to the windingof relay 217; However, through the energi'zation of'relay 411' and theattraction: of its inner left-hand armature, a groundis placed on the conductor- 426 and thence to" the other side of the Winding: of relay. 217. Hence relay 217is1short+circuited at: this. :time.

Relay 216 now attractssits armaturesand through its right-hand armaturewand" front contact again: short'Tcirc-uits thelefteha-nd windingyof' relay 405 and SlIICQrt-llB righthand': winding no longer has aholding ground; relay 405. retracts itsarmatures: llrereupon the ground for energiz-ing relay 424lis:.1'e1noveeland a' circuit isestablished from battery, thewinding of relay 424,- the frontz contact and? riirhtehand armature of relay 424; conductor 425;. normal contact of the: inner: right-hand armature: of relay 217, windingof relay. 217 ,.conductor 426, inner left-hand arm atureand: front: contact of relayr411, conductor 4-18", ri Q ht-handarmature and front contact of relay 423 to grounds Relay 217i attract-s. its armatures and through its inner; right hand armature: and alternate contactzloch'ssup to. the battery connected t0:0OnCi11CtO11218.= The movement of the: armatures of: relay 217 opensethe circuit justBtlescribed'ifOr relay 424' whereby it becomes: deenergized. The retraction, of its armaturesby. relay 4-05,..opens' a circuit for relay 421? but' since this-is a sloW-to-release relay, itdoes not retractits' armatures until after the whole series ofimpulses'have. been sent. hen relay 218 again retraetsits armatures on i the secon d" interruption of the line circuit by removing the short-circuit from around the left-hand winding-0f relay 405, relay 216 again causes the energizae lgaaecaa'r tion of relay 405.1 Again'relay 424is energized and, iniasimilar. manner," establishes a short-circuit?around the winding of: relay 219': lVhenrelay 216 attracts itsarmatures at the end of the: series of impulses, relay 405' is short-c-irouited as before and the ground is again removed from conductor 415 by the movement of the outer right-hand armature of relay 405. Counting relay 219 nowbecomes energized in series with relay 424, andtlrrough the movement ofits :n'nnrtures deenergi'zes relay 424'at the same time locking up to battery and conductor: 218;.

It Will thus be seen that two interruptions representing. the I digit 2-Willl' cause the enertgization ofthe first two counting; relays .21"? and 219,250 that'the ground \vl'llihe' extended from'the left-hand armature and back contact of thelu-st counting. relay 221', the lefthandarmature and back contact of the-next counting relay 220 and so on untilrit reaches the left armaturcand front contact of the last counting relay to beoperated,that; is, relay.219,uhere the gronndhvill be extended through: the front contact to conductor 222. In a short interyal'of' time, relay 22-3iwill be energized whereupon conductor 222 will be: extended through the armature 2'24 and frontzcontact oftrelay 223 to the \vindiiigof relay 225 Uponthe retraction of'its armatures by relay-405, thecircuzit' for relay- 421 is per; manently opened whereby after a short in terval relay 421 becomesdeenergizedi. Acirrcult is their established from ground,.the normal contacts? of the righthandarmature of relay 421, the outerileft-hand armature and front contact of: relay 422, conductor 42?, Winding ofrelay 223' to battery, Whereby relay 223 is energized With the resultant energization of'relay'225-as just: described.

Let. it be assumedtthat substation 102 is at this: time busy. A ground on the. third wire. will then be connected through the outer left-hand. armature. of relay 225. to conductor 42:8,.the right-hand arna-ature and alternate contact: of relay 422, the outer right handf armature and front contact of relay 419, the riglit-hand Winding of relay 404. to battery. Relay; 404- becomesenergized in thisscircuit; A;shortinterval after relay 421 has become deenergized,relay423 re:- tracts its armatures resulting" inthe deenergization of relay 422 a ndthe deenergization oflrelay 411wl1ereby relay 223and the counting-"relays are restored to normal, relay: 225: having locked up through: its right hand armature and'contact to groundat'the righthand'armature of relay 206*.

A sourceof'busy tone 429 is now connected throughthe back. contact and outer righthand armatureof relay 403, the front contact and middle.left han-d'armature of relay 404, the lower: normal contacts ofthe right hand armature:.-of.relay 422,. the. front: contact and outer right-hand armature-of relay 419to 3 relay 207 and it zation, of relay 1 become energized in the winding 01. relay 404, whereby through: "the inductive relation ofthe two windings of relay 404, busy tone is transmitted to the calling subscribersstation. o I

The calling subscriber now replaces his receiver on its hook whereby relay 216 bedeenergized. Since this ismore than lay back contact of relay 215, the inner left-hand armature andlfront contact of relay 207, the winding ofrelay 206, is broken so that relay "206 becomes deenergized. iThus, the ground is removed from the right-hand'winding of becomes deenergized; The ground being removed from conductor 402,

relay 419 becomes deenergized and relay 206 by openingwits'contact;at its right-hand ar-v removes the ground for holding re- 212. and 203 whereupon the con-- entirely restored .to' normal.

mature, lays 225, DQGtlOII 1s comes deenergized the circuit for theenergigroundedlead 222 to relay 225, is established the winding of relay 204,

tact of relay 225, conductor428, right-hand armature and alternate contact of relay 422, outer right-hand armature and front contact of relay 419, right-hand winding of relay 404, to battery, but neither relay 204 nor 404 i in turn relay; 422 becomes deenergized.

Thereupon this circuit is changed to lead now through the upper normal contact of the left-hand armature to, ground. This causesthe energization of 204 is energizeddirectlyfrom the ground on conductor 402 through the. outer left-hand" armature and front contact of relay 403 to "conductor 428,.relay .403 in the'meantime having locked "up through its right-hand winding, inner. armature and' front contact to conductor 429, the normal contactof the inner'left-hand armature of relay 215, front 551* contact, and rightehandlarmaturie of relay 206-;to ground. The ground on the righthandarmature of relay 403 is alsoextended through the winding of relay 430, the lefthand armature and backture and front contactplaces groundonicom du'ctor 432-which= extends to the winding of relay 433, and thencel toibattery whereby re lay 4331 becomes' energized andstarts the.

' energized.

' Talking battery 223" which connects the this circuit. In aishort interval, relay 423-becomes deenergized and;

relay operated by c and close'thelcircuit of the primary windi g contact o'f 'relayf 431 =toubattery. Belay 430 becomes ener gized and through-its inner. lett-handarmag I in this circuit and connects the groundfon" 441 through the left-hand arma ringing T914348 a will be p'ointed out erein: i after. This places ringing icurrent on' of relay' '430, front contactand inner lefthand armature ofrelay 403, through the loop of the called s and right-hand" armature of relay 430, right-f hand "winding of relay 431, conductor 434 to the other terminal-of the-source of ringing current. Ringing current flowing in this circuitis insuflicient to cause the energization of removeshis receiver from'its hook; At that time, relay 431 becomes energized and by moving its left-hand armature, short circuits relay 431 until theballed subscriber ubstation, front contact the winding of relay 430which becomes de- Relay 431 establishes a locking circuitthrough theleft-hand winding'of re; lay i431, left-hand j armature and 1 front contact of relay 431- to the ground on conductor J tablishedf" R a q is supplied to the callingline through the windings of relay 216 and 0 429. "The'conv'ersational circuit is now es 7 Let it be assumed that substation 102 1s -idle. Therefore, as sooniasrelay 421' beto the called line through the windings of book, relay 216 becomes deenergized and the connection isrestored tonormal inthe manner described. I c I I c "B'usy am and ranging circuits; I The operation ofthe busy tone and ringing circuits will now be described. When relay steadily through condenser 410 as dial tone to'the callingsubscribers and which may also betransmitted through condenser 436 to the w former and thence through the back contact and left-hand armature" ofrelay 438 to'aj ground on conductor 441 'WhlOlljIIlay be sup-- plied either at the contact and armature ofrelay 404. It'is immaterial i at this time a as before. ,A circuit will-now be established a through battery,

the outerv left-handarmature and front coni I e 401 becomes energized asbefore ,descr bed,; relay 408 is caused to buzz, placing on conductor409 a tone Wl IlOh mQJy, be transmitted primary winding 437 'ofthe busy tone trans-f;

439 orat the, contact andleft-hand ar& 1

matureofrelay 433," Relays438 and 440 arethis ground to alternately open" 437 in the following manner: WVhen ground is'placed on ;co'n'ductor441, it is extended conductor ture and front" contact of relay 440through thewinding of relay 438', thencethrough the"- ergized in this circuit. :lVhen-relay-440vbe-,

resistance 443 to -.battery. :The ienergization of -.relay 438 opens the circuit for irelay-440 whereby after a; short interval it becomes. de energized. The retraction of 2 its Jarmatnres by(relay-440. initurni opens the circuit for relay 1438 whereby after a :short interval t becomes deenergized. Tliereuponthe circuit for the ene-rgization'ofrelay 440 is again establish'ed and so on. It Willthusibeseen ithat' relays 438 and 440 are alternately-energized and deenergized and ':being slowrto-release relays, the resultant action is asslow making and breaking of the circuit including theprima-ry Windingof transformer 437.

Thus the source-of busy tone 1429 is'made periodically effective.

YThe ground on conductor 441, placed there by the left-hand armature :of relay 433, may .be periodically extended through :the rightshand armature and beer-contact of elay 440, the outer wrightrhand armature and trout-contact1of relay-i433 to conductor 444. [From thence it is extended through the right-hand armature and back contact .of relay 445, \the Winding of relay 1446, the back contacts i and inner :rlet-t-han'd armature ofirelay 445 tobattery. Relay 446 .isencomes :energized, the ground is removed ffrom conductor 444 whereupon a circuit LlS established from battery, the inner left-hand armature land 1' back contact of relay 445, -:the winding of relay 446, JfI'Ollt :contact and right hand z-Zlllflfltlllfi vof relay 446, the lefthand Winding oi'urelay 445to-ground. The current in this circuit causes the-energ1z-ation of relay 445, whereupon the right-hand Winding of relay445'is now i'ncluded'in the circuit just-c -..tr.aced. When .rclay 1440 again becomes deenergized, ground from -conduc tor- 441 :is-connected to conductor .444and thence-through (the frontcontact and righthand armatureof relay .445, .the right-hand Winding .of :relay 445 to battery. The ground connected :at this point causes the shortrcircuiting ofwthe llefthand inding of relay445-iand the winding-ctreliay 446. 'Relay 446 becomes deenergized. In a short intervalrrelay 440 again becomes 1 energized. Thereuponzthe ground i is IGHIOVEd .ctrom conductor :444 which results :in 1the;deenengization of relay 445. Itwill thus be-seen that the pair of relays i445ian'dj4'46 cooperate to close the :lefbhand armature and front conitactof lrelay 446 once ior'severyitwo :movements iQf the armature of relay 440. f In other Words; the movement of: thepairof: relays 445 and 446 ment of the :pair of relays .438 and 1440. The pair of relays .445 :and 1446 iisgused to periodically place battery through the outerv left-hand armatureand backcont-act ofzrelay 445, IthefIett h-and armature and front contactof relay 446, through conductor 447 :so that current will flow througlneither the which the energized, in :turn

.isihalt as -fast. ast hezmovee essee? rightlrand :or leftrhand primary windings of the source of-ringing current 448 to the outer left-hand armature .and contacts of relay 7-4-49, the front contact and inner :righthand armature of relay-433 toground. this battery connection to conductor 447 is thus made only whenirela-y 446 is energizednand relay 445 is deenergized andvsince this condition obtains only oncedurinu'every other closure of the rightehand armature and backcontact: of relay 440, the ringing period willzheone In other words the;. ia-i-r of :relays 4'38:and 440 --constitute :a -.pri1nary interrupter garrangeinent delivering impulses in cycles in circuit closures and the .circuit breaks are-uniform in duration and this device controls a secondary interrupter 'device, comprisingrlays 445 and 446, which delivers impulses in ,cyclesiin which 1 the circuit closures and thecircuit breaks are nonuniform :in dunation and of a lower frequency ithan the impulses delivered by :the said primary interrupterdevice. The pair ofrelays 449 and 450 not in exactlyithe same manner as the :pair of relays e438 .an'd 440. Both (being itast' relays, ntheir vibration is fast-enough to .causerthe currents flowing in the primary windings of :the transformer 448 to. set up an alternating current of 1 the proper frequency for :ringing purposes in the secondary iivindings .ot theztransfornier 448.

Thus, when :a :relay such as 430 becomes causing the relay 43310 become energized, 'rthe :ringing rrelays are started and a source of ringing current is placed-on conductors .434iand 445. 'VVlien a called linehas been :fountlilmsy,racircuit is established :from ground, xwindin g of relay 401, winding =of relay +439, ssec'ondary of transformer 5&9, "conductor 1451, back contact and router right-.hzand armature :of relay :403, front :contact and middle ilefthand armature of :relay I404, lower normal xoontacts oiirelay 422, 'front ecent-act and I outer right-hand armature of relay 419, righthand winding :of relay 4ti4 ito battery. lhis causes the energimtion of=relay 4 01 and 439 whereby :a source: of I busy .itone 429 2 is made effective .and through the inductive 'rela-tion of the windings (of :relay 404 Ihusy (tone is transmitted to i the calling subscriber.

VA system 'otzthis character may 1 be adapted :for trunk i connections with central 'oflice equipment as :disclosed :in the above mentioned Patent 1:;507i1l6 granted :September 2,1924. J

hat is claimed fisz.

1. In aitelephonesystem, an interrupting device comprising :a ipairsofarelaysrarranged I in :a circuit with-means controlled tbyieach ly, and interrupting icontacts ."eontrolled by third n-slong' as: the silent period.

said relays, in a circuit including saidcontacts whereby two successive closures and openings of said.

contacts will cause said other pair of relays to be successively actuated in all possible combinations and a'circuit periodically controlled by said second pair of relays.

2. In a telephone system, an interrupting device comprising a pairof relays arranged in a circuit with said relays operate periodically and automatically, and interrupting contacts con trolled by said relays, at auniform rate, another pair of relays arranged in a circuit including" said contacts whereby two succe s-k sive closures and openings of said contacts mcomprising a ringing current generator and e an interrupting device,

will cause said other pair. ofrelaysto be suc-j cessively actuated in all possible combina' tions and contacts controlled by said other pair ofrelays in non-uniform periods.

3. In a telephone system, aringing device pair of relays to be successively actuated in all possible combinations and a circuitineluding said ringing current generator periodically controlled by said second pair oiv relays.

4. In a telephone system, a" ringing devvice, comprising a ringing current genera-1 said interrupting device comprising a pair of relays tor and an-iiiterrupting device,

another pair of relays arranged means controlled by each 3 ,relay for controlling the other, whereby said interrupting and interrupting contacts controlled arranged in a circuit with means controlled by each relay for controlling the other, whereby said'relays periodically andautomatically, at a .uniforinrate and interrupting. contacts controlled by said relays, another pair of relays arranged in a circuit including said contactswhereby two successive closures and openings of said contactswillcause said-otherpair of relays to be successivelyaotuated in all possible. coinbi- 1 nations-and a circuit includingsaid ringing current generatorjcontrolled by said second pair of relays in non-uniform periods.

5. Ina telephone system, a ringing device comprising ,a ringing an interrupting device,

a transformer, said relays being arranged in a circuit with means controlled by each relay for controlling the circuiteofthe other, wherebysaid relays operate periodi- 'cally and automatically,

said relays controlling a switching device for alternately energiz ling different windings of said trans former,

current generator and sa d ring ng current generator comprising an arrangement-oi relays and said interrupting device comprisingja pair of relays-arranged in a circuit.

with "means controlling the other, whereby said relays operate periodically; and automatically and interrupting contacts controlled by saidrelays,"

be successively actuated in all possible combinations'and a circuit including said transformer windings periodically controlled .by said second pair of relays.

my name this 25th 1923. 1 i I EDWARD E. HINRICHSEN.

controlled :by each relay for i ,anotherpair ofrelays arranged ina circuit including said contactswherebytwo successive closures and openings ofsaid con-I tacts Willcau'sesaid other pair of relays to In witness ,whereof, I hereunto subscribe. .day'of September D. 

